Adjustable shelf



FIG. 1 is a front, bottom and right side perspective view of an adjustable shelf showing my new design;

FIG. 2 is a front, bottom and right side partial perspective view thereof;

FIG. 3 is a front plan view of the partial view shown in FIG. 2;

FIG. 4 is a top view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a back plan view thereof; and,

FIG. 7 is a bottom view thereof.

The broken-line disclosure is understood to represent unclaimed portions of the article in which the claimed design is embodied. 

The ornamental design for an adjustable shelf, as shown and described. 